Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758049Ab0BMVHZ (ORCPT ); Sat, 13 Feb 2010 16:07:25 -0500 Received: from mail-pz0-f197.google.com ([209.85.222.197]:33781 "EHLO mail-pz0-f197.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752700Ab0BMVHY convert rfc822-to-8bit (ORCPT ); Sat, 13 Feb 2010 16:07:24 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=afGp56sDCAKgKzvaG1gq8pX3cKyc9UwmDtji/529F85i2lEtDz0oFNYfufiys85DUy QaKTlFt3ocGVqAqyOKyxrDduB2z5eEDPL5NZq8ZEGai+iT9t3GDcMf5rqDN6ROln5CA7 rCpnwEcREoQHiw8wHb63zVMpP6/VuQDQXgzK8= MIME-Version: 1.0 In-Reply-To: References: <4877c76c1002111752h23e14f7aibe58a89181e6f493@mail.gmail.com> <4B77044B.1020609@zytor.com> Date: Sat, 13 Feb 2010 13:07:22 -0800 Message-ID: <4877c76c1002131307i61a3c985w8db8c10623a693c8@mail.gmail.com> Subject: Re: Linux mdadm superblock question. From: Michael Evans To: david@lang.hm Cc: Justin Piszcz , "H. Peter Anvin" , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2514 Lines: 68 On Sat, Feb 13, 2010 at 12:49 PM, wrote: > On Sat, 13 Feb 2010, Justin Piszcz wrote: > >> On Sat, 13 Feb 2010, H. Peter Anvin wrote: >> >>> On 02/11/2010 05:52 PM, Michael Evans wrote: >>>> >>>> On Thu, Feb 11, 2010 at 3:00 PM, Justin Piszcz >>>> wrote: >>>>> >>>>> Hi, >>>>> >>>>> I may be converting a host to ext4 and was curious, is 0.90 still the >>>>> only >>>>> superblock version for mdadm/raid-1 that you can boot from without >>>>> having to >>>>> create an initrd/etc? >>>>> >>>>> Are there any benefits to using a superblock > 0.90 for a raid-1 boot >>>>> volume >>>>> < 2TB? >>>>> >>>>> Justin. >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe linux-raid" >>>>> in >>>>> the body of a message to majordomo@vger.kernel.org >>>>> More majordomo info at ?http://vger.kernel.org/majordomo-info.html >>>>> >>>> >>>> You need the superblock at the end of the partition: ?If you read the >>>> manual that is clearly either version 0.90 OR 1.0 (NOT 1.1 and also >>>> NOT 1.2; those use the same superblock layout but different >>>> locations). >>> >>> 0.9 has the *serious* problem that it is hard to distinguish a >>> whole-volume >>> >>> However, apparently mdadm recently switched to a 1.1 default. ?I >>> strongly urge Neil to change that to either 1.0 and 1.2, as I have >>> started to get complaints from users that they have made RAID volumes >>> with newer mdadm which apparently default to 1.1, and then want to boot >>> from them (without playing MBR games like Grub does.) ?I have to tell >>> them that they have to regenerate their disks -- the superblock occupies >>> the boot sector and there is nothing I can do about it. ?It's the same >>> pathology XFS has. >>> >>> ? ? ? ?-hpa >>> >> >> My original question was does the newer superblock do anything special or >> offer new features *BESIDES* the quicker resync? > > the older superblocks have limits on the number of devices that can be part > of the raid set. > > David Lang > The 1.1 and 1.2 formats ALSO play more nicely with stacking partition contents. LVM, filesystems, and partition info all begin at the start of a block device; putting the md labels there too makes it obvious what order to unpack the structures in. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/